U.S. patent number 4,524,637 [Application Number 06/400,715] was granted by the patent office on 1985-06-25 for spring-operated mechanism.
This patent grant is currently assigned to Mitsubishi Denki Kabushiki Kaisha. Invention is credited to Toshiaki Yoshizumi.
United States Patent |
4,524,637 |
Yoshizumi |
June 25, 1985 |
Spring-operated mechanism
Abstract
A spring-operated mechanism for actuating a switch gear, etc.
comprises a cam member secured to a crankshaft and adapted to be
moved thereby. Cam grooves are formed in the cam member such that
the distance from the center of the crankshaft is smallest at the
middle portion of the groove and progressively increases towards
the extremities of the groove. A rod is provided with a pin at one
end adapted to be rolled at each end within the cam grooves, and at
the other end the rod is provided with a spring support. A
stationary member is provided with guide elements to cause the rod
to move linearly, and a spring is disposed between the stationary
member and the spring support, whereby the spring is adapted to
store compressive energy when the crankshaft is rotated through a
predetermined angle by a driving source, and, through a further
revolution of the crankshaft, the spring releases the stored energy
to accelerate the revolution of the crankshaft.
Inventors: |
Yoshizumi; Toshiaki (Minoo,
JP) |
Assignee: |
Mitsubishi Denki Kabushiki
Kaisha (Tokyo, JP)
|
Family
ID: |
25803347 |
Appl.
No.: |
06/400,715 |
Filed: |
July 22, 1982 |
Current U.S.
Class: |
74/569;
74/100.1 |
Current CPC
Class: |
F16H
21/38 (20130101); H01H 3/30 (20130101); Y10T
74/18896 (20150115); Y10T 74/2107 (20150115) |
Current International
Class: |
F16H
21/38 (20060101); F16H 21/00 (20060101); H01H
3/30 (20060101); H01H 3/00 (20060101); F16H
053/06 (); F16H 025/18 () |
Field of
Search: |
;74/569,104,105,107,100,97 ;200/67A,153SC |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
55-46609 |
|
Apr 1976 |
|
JP |
|
159511 |
|
Dec 1980 |
|
JP |
|
157417 |
|
Sep 1982 |
|
JP |
|
Primary Examiner: Dorner; Kenneth J.
Attorney, Agent or Firm: Wenderoth, Lind & Ponack
Claims
What is claimed is:
1. A spring-operated mechanism comprising:
a cam means secured to a crankshaft and adapted to be moved
thereby,
cam grooves formed in said cam means having such a shape that the
distance from a center of said crankshaft is smallest at a middle
portion of said cam grooves and progressively increases towards
extremities of said cam grooves,
a connecting rod provided with a guide roller at one end rolling
within said cam grooves,
a spring rod provided at the other end of the connecting rod,
a bottom spring support connected to the spring rod at an end
opposite from the connecting rod,
a stationary member provided with groove means at the other end of
the connecting rod for guiding rectilinear movement of said
connecting rod, and
a spring support means disposed between said stationary member and
said bottom spring support,
whereby said spring means is adapted to accumulate energy when said
crankshaft is rotated through a predetermined angle by a driving
source, and, upon further revolution of said crankshaft, said
spring means releases said energy to urge said crankshaft to rotate
quickly.
2. A spring-operated mechanism as claimed in claim 1 wherein:
said spring rod is pivotally connected to said connecting rod by a
connecting pin.
3. A spring-operated mechanism as claimed in claim 2 wherein said
connecting pin is provided with at each end a roller which is
adapted to be moved rectilinearly along said groove means upon
rotation of said crankshaft.
4. A spring-operated mechanism comprising:
a cam means secured to a crankshaft and adapted to be moved
thereby,
cam grooves formed in the cam means having such a shape that the
distance from a center of the crankshaft is smallest at a middle
portion of the cam grooves and progressively increases towards
extremities of the cam grooves,
a spring rod provided with a guide roller at one end rolling within
the cam grooves and provided at the other end with a spring
support,
a spring case provided with an opening to allow rectilinear
movement of the spring rod therethrough, and
a spring means contained inside the spring case above the spring
support,
whereby the spring means is adapted to accumulate energy when the
crankshaft is rotated through a predetermined angle by a driving
source, and, upon further revolution of the crankshaft, said spring
means releases the energy to urge the crankshaft to rotate quickly.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spring-operated mechanism and
more particularly to a spring-operated mechanism for actuating a
switch gear, etc. although not limited thereto.
2. Description of the Prior Art
As the voltage and capacity in electric transmission and substation
systems have increased, the switch gears have also tended to become
larger, requiring an operating apparatus having a large output to
drive the switch gears. Hitherto, for operating apparatus having
large output, fluid operating systems such as pneumatic or
hydraulic operating systems have been most common and motor-driven
spring-operated systems have also been utilized for relatively
small outputs.
However, a fluid operating system is inferior to a motor-driven
spring-operated system from the standpoint of maintenance. For
example, the former has such practical problems as the maintenance,
inspection, etc. of a compressor in a pneumatic system, or
lubricant leakage at connections of the piping, etc. in a hydraulic
system.
As a motor-driven spring-operated system, one using a toggle joint
has been hitherto widely used. Examples of principal elements and
the operational principle thereof are schematically indicated in
FIGS. 1 and 2, respectively. Now the features of a conventional
motor-driven spring-operated apparatus utilizing a toggle joint
will be explained below in reference to FIGS. 1 and 2.
The operational principle is shown in FIGS. 2A-2D as follows:
(i) Upon receiving a demand for operation, a motor (not shown)
begins to rotate, and the torque is transmitted to a motor lever 1
through a reduction gear (not shown);
(ii) As motor lever 1 comes into contact with one of projections 2a
of a spring lever 2 as shown in FIG. 2A, a spring 5 now being at a
point of maximum elongation is gradually compressed by the torque
of motor lever 1 to store energy therein and reaches a point of
maximum compression as shown in FIG. 2B, whereby spring 5 is
disposed within a spring casing pivotally mounted to a stationary
member through pivots 5a in parallel with an output shaft 4.
Another projection 2b of spring lever 2 abuts against an output
shaft lever 3 when spring 5 for the first time reaches the point of
maximum compression;
(iii) After reaching the point of maximum compression, spring 5
begins to release the stored energy to accelerate output shaft
lever 3 through spring lever 2; and
(iv) When spring 5 again reaches the point of maximum elongation
(in a position such that the inclination of spring 5 with respect
to the vertical axis is just opposite that at the initiation of the
operation.) the operation is completed as shown in FIG. 2C.
The reverse operation takes place similarly starting from the state
shown in FIG. 2D by repeating the operations described above in the
rearward direction.
Thus it will be appreciated that a spring-operated system of the
toggle joint type has a simple operational principle, has few
components, and thus exhibits superiority from the viewpoint of
economy. In general, in switch gears, in particular in one provided
with the ability to break an electric current, in order to obtain a
sufficient initial separation speed, a large amount of energy is
required at the initial phase of the operation. However, with a
spring-operated system of the toggle joint type shown in FIGS. 1
and 2, since the released energy of spring 5 at the initial phase
of the operation corresponding to the rotation of output shaft 4
for a predetermined angle is less than that during its operation,
it is difficult to obtain a sufficient initial separation speed. In
order to obviate such a difficulty it is conceivable that the
maximum compressive load of the toggle joint spring can be set
higher. However, in this case, it is necessary to absorb the excess
energy accumulated in the moving parts of the switch gear at the
time of the completion of the operation by the use of a damping
means etc., and new problems occur such as increasing oscillations
of the system at the completion of the operation due to impact
force.
In order to remedy the difficulties inherent to the conventional
spring-operated mechanisms as discussed above, Japanese Patent
Publication No. 46609/1980 (filed on Aug. 15, 1975, claiming the
priority of West German Patent Application No. P2439837.6 filed on
Aug. 16, 1974, by Siemens A.G., entitled "A Snap Type Driving
Apparatus for a Switch Gear", published on Nov. 25, 1980) discloses
a mechanism wherein the parts participating in closing or opening
the switch gear are disposed in a concentric manner so as to be
rotatable, and further both of the parts are provided with concave
portions so as to be engageable by an engaging pin connected to the
energy storing spring.
Further, Japanese Laid-Open Patent Publication No. 15 9511/1980
(filed on May 31, 1979 by Tokyo Shibaura Denki Co., Ltd., entitled
"A Motor Drive Spring-Operated Apparatus", laid-open on Dec. 11,
1980) discloses a mechanism wherein a crank pin connected to and
driven by an electric motor is adapted to rotate a rotational shaft
by a link engaging the crank pin through a slot and a lever pivoted
to the link and connected to the shaft so that the torque of the
electric motor causes a spring to store energy by means of the
rotational shaft.
However, none of them teach or suggest the use of cam means in a
spring-operated mechanism in order to make the spring release the
major part of the stored energy at the initial phase of the
operation of the mechanism as in the present invention.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a spring-operated
mechanism which does not have the defects of the conventional
mechanism as discussed above.
Another object of the present invention is to provide a
spring-operated mechanism which is applicable to operate a switch
gear or similar device that requires large operational force at the
initial phase of the operation.
A further object of the present invention is to provide a
spring-operated mechanism which can make the initial separation
speed higher than in the conventional mechanism when it is used in
association with a switch gear.
In accordance with the present invention a spring-operated
mechanism is provided which comprises a cam secured to a crankshaft
and adapted to be moved thereby, cam grooves formed therein, a rod
provided with a pin at one end adapted to be rolled within the cam
grooves and at the other end a spring support, a stationary member
provided with means to guide the rod along a rectilinear course,
and a spring disposed between the stationary member and the spring
support, whereby the spring is adapted to store energy when the
crankshaft is rotated through a predetermined angle by a driving
source, and, upon further revolution of the crankshaft beyond the
predetermined angle, the spring releases the stored energy to cause
the crankshaft to be rotated quickly.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages of this invention will become apparent
from the following description considered along with the
accompanying drawings wherein are set forth by way of illustration
and example certain embodiments of this invention, in which:
FIG. 1 is a schematic exploded representation of a conventional
motor-driven spring-operated mechanism as used for operating a
switch gear;
FIGS. 2A to 2D are representations of the sequential states of the
main components of the mechanism shown in FIG. 1 to illustrate its
operational principle;
FIG. 3 is a schematic exploded representation of one embodiment of
the present invention as used for actuating a switch gear;
FIGS. 4A to 4E are representations of the sequential states of the
main components of the mechanism shown in FIG. 3 to illustrate its
operational principle;
FIG. 5 illustrates characteristic curves of the conventional
mechanism shown in FIGS. 1 and of 2 and the mechanism in accordance
with the present invention shown in FIGS. 3 and 4; and
FIG. 6 is a view of another embodiment of the present invention,
with the inside of the spring casing partially exposed.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 3 wherein an embodiment of the present
invention is schematically shown, it should be noted that in order
to facilitate the understanding of the present invention, levers,
etc. which are originally in contact with each other are shown
separated from each other, and the casing for the mechanism, an
electric motor, a reduction gear box, bearings, etc. are all
omitted.
In FIG. 3, the reference numeral 7 denotes a motor lever to
transmit motor torque given thereto from an electric motor through
a reduction gear, motor lever 7 being adapted to abut against a
spring lever 8 while the former rotates through a predetermined
rotational angle from the initial point. Therefore, the rotational
axes of motor lever 7 and spring lever 8 are disposed in a line.
Spring lever 8 and a cam lever 11 are rigidly connected on a line
through a crank mechanism comprising crankshafts 10a, 10b and a
pair of separated confronting crank arms 9, each having a sector
form with the peripheral portions thereof being connected together
and rigidly connected at their outer portions to confronting ends
of the crankshafts 10a, 10b. The other ends of the crankshafts 10a,
10b are rigidly connected to spring lever 8 and cam lever 11,
respectively. In this embodiment, each of crank arms 9 has a sector
form with its center of rotation coinciding with the centers of
crankshafts 10a and the two crank arms 9 are adapted to act
together as a cam member. For this purpose each of them is formed
with a cam groove 9a therein so that the grooves 9a are aligned
with each other with a gap being left therebetween, cam groove 9a
having generally a heart shape with its longitudinal center line
lying on the bisector of the sector and with the "point" of the
"heart" facing towards the axes of crankshafts 10a, 10b.
In other words, cam groove 9a has such a shape that the distance
from the center of the crankshaft 10a, 10b is smallest at the
middle portion of the groove 9a and progressively increases towards
the extremities of the groove 9a. A rod-like cam follower 14a
provided at each end with a guide roller 14 is disposed within the
gap between crank arms 9 so that guide rollers 14 are rotatively
guided with cam grooves 9a.
One end of a connecting rod 15 is rotatably connected to cam
follower 14a, and the other end of connecting rod 15 is rotatably
connected to a spring rod 17. For this purpose, both ends of
connecting rod 15 are pivotally connected to cam follower 14a, and
a pin 16a, respectively, pin 16a pivotally connecting one of the
ends of connecting rod 15 and spring rod 17. Pin 16a carries at
each end a roller 16. A stationary roller guide 20 comprising a
pair of confronting parallel transverse plates and secured to the
casing of the mechanism is provided with vertical grooves 20a in
both confronting plates so as to guide rollers 16 of pin 16a to
move rectilinearly.
A spring support 19, carrying one end of a spring 18, is fixedly
secured to roller guide 20. Another spring support 21, carrying the
other end of spring 18, is fixedly secured to the free end of
spring rod 17. An output shaft lever 12 lying coaxially to cam
lever 11 is adapted to transmit the torque of cam lever 11 due to
the release of the stored energy of spring 18 to be described
later.
The operation of the motor-driven spring-operated mechanism
described above and illustrated in FIG. 3 will be explained with
reference to FIGS. 4A to 4E which schematically represent the
sequential states of the main components of the mechanism shown in
FIG. 3 to illustrate its operational principle. In FIGS. 3 and 4
the same reference numerals denote similar or corresponding
members.
(a) Upon receiving an operation command, the motor (not shown)
begins to rotate motor lever 7 from the state shown in FIG. 4A, the
motor torque being transmitted to motor lever 7 through the
reduction gear (not shown), and motor lever 7 causes spring lever 8
abutting thereto to be rotated;
(b) Since the cam or crank arms 9 and cam lever 11 are connected to
spring lever 8 through crankshafts 10a and 10b, they are caused to
rotate as spring lever 8 rotates. At this time, cam follower 14a
shifts upwards as viewed in FIG. 4B with guide rollers 14 being
guided along cam grooves 9a as crank arms 9 rotate so that spring
18 is compressed between spring supports 19 and 21 through
connecting rod 15 and spring rod 17. Thus, spring 18 reaches height
h as shown in FIG. 4B;
(c) Motor lever 7 is adapted to stop its rotation after it carries
out a small rotation after spring 18 has reached a state of maximum
compression. This small rotation causes a small elongation
(e.sub..degree.) of spring 18. At this time, since the cam or crank
arms 9 have passed their top dead centers, they continue to rotate
further due to the release of the energy stored in spring 18, cam
follower 14a being simultaneously urged to the position shown in
FIG. 4C. In this case, the released energy of spring 18 is a small
value corresponding to the stroke e.sub..degree. of spring 18 as
shown in FIG. 4C. Therefore, the impact due to the collision of
guide rollers 14 of cam follower 14a with the bottoms of cam
grooves 9a is very small. At this stage, cam lever 11 for the first
time comes into contact with output shaft lever 12 as shown in FIG.
4C;
(d) The cam or crank arms 9 are accelerated and quickly moved
through spring rod 17 and connecting rod 15 due to the release of
the energy stored in spring 18 as shown in FIG. 4D. Simultaneously
output shaft lever 12 and output shaft 13 (FIG. 3) are quickly
moved as cam lever 11 connected to crankshaft 10b through crank
arms 9 rotates, output shaft lever 12 being rotated through an
angle .theta..sub.1 as shown in FIG. 4D;
(e) Spring 18 continues to release the accumulated energy until it
reaches a state of maximum elongation as shown in FIG. 4E. At this
stage of the operation the cam or crank arms 9 occupy a position in
symmetry with that at the time of the start of the operation shown
in FIG. 4A, output shaft lever 12 rotating further through angle
.theta..sub.2 as shown in FIG. 4E;
(f) By reversing the rotation of the motor to reversely rotate
motor lever 7, a reverse operation can be carried out in a manner
similar to the procedures (a) to (e) described above.
As will be understood, with the motor-driven spring-operated
mechanism in accordance with the present invention, as shown in
FIGS. 4A to 4E, since the stroke e.sub.1 of spring 18 corresponding
to the rotational angle .theta..sub.1 of output shaft lever 12
during the first half of the operation is larger than the spring
stroke e.sub.2 corresponding to the rotational angle .theta..sub.2
of output shaft lever 12 during the last half of the operation, it
is advantageous in quickening the initial separation velocity in a
switch gear. Further, at the time of the completion of the
operation, since the energy to be stored in the moving parts of the
switch gear is less than that of a conventional switch gear, there
arises another advantage that no dampers, etc. need be utilized to
absorb excessive energy.
FIG. 5 graphically represents the above advantages of the present
invention over a conventional system. The sum of the energy
released by the spring is plotted against the angle of rotation of
the output shaft for an angle of rotation of up to 90.degree.. In
FIG. 5, the angle .phi. represents the rotational angle of the
output shaft necessary for obtaining a predetermined initial
separation velocity, and P.sub.2 represents the energy necessary
for obtaining the same. P.sub.1 represents the energy to be given
to the output shaft during the rotation through the angle .phi. in
a conventional spring-operated mechanism of the toggle joint type
(assuming that the spring force is adjusted to correspond to the
case of the present invention).
As will be apparent from FIG. 5, in a motor-driven spring-operated
mechanism in accordance with the present invention, the released
energy of the spring is larger at the initial phase of the rotation
of the output shaft, rapidly decreasing as the rotation of the
output shaft progresses. Contrarily, in a conventional motor-driven
spring-operated mechanism of the toggle joint type, the released
energy of the spring is high midway through the rotation of the
output shaft. Therefore, if the sum of the discharged energy of the
spring is assumed to be constant, the initial separation velocity
in a conventional mechanism is lower than that in the mechanism in
accordance with the present invention.
Further, in a conventional mechanism, as shown by the dot-and-dash
line in FIG. 5, if it is attempted to achieve the predetermined
separation velocity by increasing the spring pressure, excessive
energy must be accumulated in the moving parts of the mechanism,
causing problems such as oscillation at the time of the completion
of the operation.
From the foregoing, as will be apparent, with the motor-driven
spring-operated mechanism in accordance with the present invention,
a very large operational force compared with that of the
conventional mechanism of the toggle joint type (more than roughly
two times the force in the conventional mechanism) can be obtained
by the use of spring pressure substantially identical to that of
the conventional system. The present invention also has the
advantage of suppressing to a low level the oscillation, etc. at
the time of the completion of the operation.
Therefore, if the mechanism according to the present invention is
utilized for the purpose of obtaining an operation force similar to
that obtainable in a conventional mechanism, it is possible to have
the spring pressure much lower than that in a conventional
mechanism, remarkably decreasing oscillations, etc. at the time of
the completion of the operation.
In the embodiment shown in FIG. 3, for the purpose of removing the
energy loss due to the oscillations of the spring, rollers 16
mounted to pin 16a pivotally connecting spring rod 17 to connecting
rod 15 are constrained by roller guides 20 so that the movement of
spring 18 is made linear. However, in a modified embodiment of the
present invention, as shown in FIG. 6, spring rod 17 and cam
follower 14a may be directly connected without intervening
connecting rod 15. It will be appreciated that this modified
embodiment can reveal the effects similar to those in the first
embodiment. In FIG. 6 the reference numeral 22 shows a spring
casing and the reference numeral 23 shows pivots which pivotally
mount spring casing 22 to the housing of the mechanism, crankshafts
10a, 10b being maintained always in a prescribed positional
relationship as in the first embodiment.
While there are described and illustrated herein a few preferred
embodiments of the present invention it will be understood that
modifications may be made without departing from the spirit of the
present invention.
* * * * *